StellarSolver for Android?

[laheller]

Hi @rlancaste

This is not an issue, just a question.

What do you think, is it possible to build this library for Android platform using the Android NDK?

BR,

Ladislav

[rlancaste]

So that I do not know, I do not have any experience with that. A big first question is whether all the dependencies are supported on Android. If so, then it could be possible.

[laheller]

Hi @rlancaste

The library mentioned in this comment is NOT a dependency of astrometry.net but it has a detailed description, how to build a library using NDK for Android platform. Can be used as a starting point. I also will try start with dependencies one by one and build them.

[rlancaste]

Would the idea for this be to have it included in KStars for Android?

[laheller]

Yes. Or just simply to have a plate solver for Android.

Update: I was able to build following dependencies for Android:

• gsl
• cairo
• cfitsio
• wcslib
• netpbm (not really needed for astrometry.net, but I just built it, even when it was a bit tricky)

[laheller]

@rlancaste

I have an Android build of astrometry.net that seems to be working at least partially. Now trying the pure binaries (including also the dependency libraries and some index files) directly on my Samsung Galaxy S20+ device (rooted).
The plate solving fails somehow at the astrometry-engine binary.

Output from Android Terminal:

y2s:/data/local/tmp/astrometry.net # ./astrometry-engine -v ../Solve/Sas.axy
Config file "./../etc/astrometry.cfg" doesn't exist.
Using config file "./astrometry.cfg"
Auto-indexing directory "/data/local/tmp/index_files" ...
Skipping directory /data/local/tmp/index_files/.
Skipping directory /data/local/tmp/index_files/..
Checking file "/data/local/tmp/index_files/index-4107.fits"
Index name "/data/local/tmp/index_files/index-4107.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4108.fits"
Index name "/data/local/tmp/index_files/index-4108.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4109.fits"
Index name "/data/local/tmp/index_files/index-4109.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4110.fits"
Index name "/data/local/tmp/index_files/index-4110.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4111.fits"
Index name "/data/local/tmp/index_files/index-4111.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4112.fits"
Index name "/data/local/tmp/index_files/index-4112.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4113.fits"
Index name "/data/local/tmp/index_files/index-4113.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4114.fits"
Index name "/data/local/tmp/index_files/index-4114.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4115.fits"
Index name "/data/local/tmp/index_files/index-4115.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4116.fits"
Index name "/data/local/tmp/index_files/index-4116.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4117.fits"
Index name "/data/local/tmp/index_files/index-4117.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4118.fits"
Index name "/data/local/tmp/index_files/index-4118.fits" is readable, using as index filename
Checking file "/data/local/tmp/index_files/index-4119.fits"
Index name "/data/local/tmp/index_files/index-4119.fits" is readable, using as index filename
Trying to add index "/data/local/tmp/index_files/index-4119.fits".
Index name "/data/local/tmp/index_files/index-4119.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4119.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4119.fits" is readable, using as index filename
Index scale: [1400, 2000] arcmin, [84000, 120000] arcsec
Index has 1728 quads and 1080 stars
Trying to add index "/data/local/tmp/index_files/index-4118.fits".
Index name "/data/local/tmp/index_files/index-4118.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4118.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4118.fits" is readable, using as index filename
Index scale: [1000, 1400] arcmin, [60000, 84000] arcsec
Index has 3072 quads and 1920 stars
Trying to add index "/data/local/tmp/index_files/index-4117.fits".
Index name "/data/local/tmp/index_files/index-4117.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4117.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4117.fits" is readable, using as index filename
Index scale: [680, 1000] arcmin, [40800, 60000] arcsec
Index has 4800 quads and 3000 stars
Trying to add index "/data/local/tmp/index_files/index-4116.fits".
Index name "/data/local/tmp/index_files/index-4116.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4116.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4116.fits" is readable, using as index filename
Index scale: [480, 680] arcmin, [28800, 40800] arcsec
Index has 9408 quads and 5880 stars
Trying to add index "/data/local/tmp/index_files/index-4115.fits".
Index name "/data/local/tmp/index_files/index-4115.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4115.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4115.fits" is readable, using as index filename
Index scale: [340, 480] arcmin, [20400, 28800] arcsec
Index has 19200 quads and 12000 stars
Trying to add index "/data/local/tmp/index_files/index-4114.fits".
Index name "/data/local/tmp/index_files/index-4114.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4114.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4114.fits" is readable, using as index filename
Index scale: [240, 340] arcmin, [14400, 20400] arcsec
Index has 37632 quads and 23520 stars
Trying to add index "/data/local/tmp/index_files/index-4113.fits".
Index name "/data/local/tmp/index_files/index-4113.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4113.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4113.fits" is readable, using as index filename
Index scale: [170, 240] arcmin, [10200, 14400] arcsec
Index has 76800 quads and 48000 stars
Trying to add index "/data/local/tmp/index_files/index-4112.fits".
Index name "/data/local/tmp/index_files/index-4112.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4112.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4112.fits" is readable, using as index filename
Index scale: [120, 170] arcmin, [7200, 10200] arcsec
Index has 150528 quads and 94080 stars
Trying to add index "/data/local/tmp/index_files/index-4111.fits".
Index name "/data/local/tmp/index_files/index-4111.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4111.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4111.fits" is readable, using as index filename
Index scale: [85, 120] arcmin, [5100, 7200] arcsec
Index has 292032 quads and 182520 stars
Trying to add index "/data/local/tmp/index_files/index-4110.fits".
Index name "/data/local/tmp/index_files/index-4110.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4110.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4110.fits" is readable, using as index filename
Index scale: [60, 85] arcmin, [3600, 5100] arcsec
Index has 580800 quads and 362959 stars
Trying to add index "/data/local/tmp/index_files/index-4109.fits".
Index name "/data/local/tmp/index_files/index-4109.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4109.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4109.fits" is readable, using as index filename
Index scale: [42, 60] arcmin, [2520, 3600] arcsec
Index has 1168066 quads and 724260 stars
Trying to add index "/data/local/tmp/index_files/index-4108.fits".
Index name "/data/local/tmp/index_files/index-4108.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4108.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4108.fits" is readable, using as index filename
Index scale: [30, 42] arcmin, [1800, 2520] arcsec
Index has 2320889 quads and 1291539 stars
Trying to add index "/data/local/tmp/index_files/index-4107.fits".
Index name "/data/local/tmp/index_files/index-4107.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4107.fits" is readable, using as index filename
Index name "/data/local/tmp/index_files/index-4107.fits" is readable, using as index filename
Index scale: [22, 30] arcmin, [1320, 1800] arcsec
Index has 4454259 quads and 1909957 stars
Reading file "../Solve/Sas.axy"...
Set odds ratio to solve to 1e+09 (log = 20.7233)
Couldn't allocate memory for a bl node!
Segmentation fault
134|y2s:/data/local/tmp/astrometry.net #

The above error message comes from the bl.c source file. Is there any option or switch to force astrometry to use less memory? Or I don't know, what to do with this error.

Anyway I will try to rebuild while experimenting with the build settings.

BR,

Ladislav

[laheller]

@rlancaste

FYI, I successfully built the whole astrometry.net including dependencies. Tested were following tools from suite:

• solve-field
• astrometry-engine
• wcsinfo
• plot-constellations

All of them worked perfectly!

Question is, what's next?

BR,

Ladislav

[rlancaste]

Ah that's cool. So next would be to see if we can build StellarSolver on Android or if we have to make any changes to make it work there. If it does work on Android, then we could include plate solving and Ekos on Android perhaps

[rlancaste]

So I just asked Jasem about it and he said that there isn't anybody currently working on or maintaining KStars for Android. While we could certainly get StellarSolver working for android, based on your success so far, the issue would be that next step.

[laheller]

@rlancaste

OK, I will try to build StellarSolver for Android (armv7a and aarch64 architectures) and let you know.
BTW when I build it, I should get a shared library, something like libStellarSolver.so, right?

Android NDK has LLVM toolchain with clang compiler, it works pretty much the same way, as in Linux.

[rlancaste]

If you just build the library you should get libstellarsolver in the lib directory, as well as some include files in the StellarSolver subfolder of the include directory. If you also build the tester, then you should get StellarSolverTester in the bin directory

[laheller]

Hi @rlancaste

Trying to build StellarSolver for Android platform, and the cmake somehow can't find the gsl library, but it founds cftitsio.

Here is how I call cmake:

#! /bin/bash

# Set these variables to suit your needs
NDK_PATH=/home/laheller/android-ndk-r23b
TOOLCHAIN="clang"
ANDROID_VERSION="29"

export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:${HOME}/android-repos/gsl/_deploy_aarch64/lib/pkgconfig
export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:${HOME}/android-repos/cfitsio-4.0.0/_deploy_aarch64/lib/pkgconfig
export PKG_CONFIG_PATH=${PKG_CONFIG_PATH}:${HOME}/android-repos/wcslib-7.7/_deploy_aarch64/lib/pkgconfig

export CFLAGS="-fPIC -std=c17"

cmake -G"Unix Makefiles" \
    -DANDROID_ABI=arm64-v8a \
    -DANDROID_PLATFORM=android-${ANDROID_VERSION} \
    -DANDROID_TOOLCHAIN=${TOOLCHAIN} \
    -DCMAKE_ASM_FLAGS="--target=aarch64-linux-android${ANDROID_VERSION}" \
    -DCMAKE_TOOLCHAIN_FILE=${NDK_PATH}/build/cmake/android.toolchain.cmake \
    -DCMAKE_INSTALL_PREFIX=$(pwd)/../_deploy_aarch64 \
    ..

...and here is the output:

-- Android: Targeting API '29' with architecture 'arm64', ABI 'arm64-v8a', and processor 'aarch64'
-- Android: Selected unified Clang toolchain
-- The C compiler identification is Clang 12.0.8
-- The CXX compiler identification is Clang 12.0.8
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /home/laheller/android-ndk-r23b/toolchains/llvm/prebuilt/linux-x86_64/bin/clang - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /home/laheller/android-ndk-r23b/toolchains/llvm/prebuilt/linux-x86_64/bin/clang++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error: TRY_RUN() invoked in cross-compiling mode, please set the following cache variables appropriately:
RUN_RESULT_2 (advanced)
For details see /home/laheller/android-repos/stellarsolver/_build/TryRunResults.cmake
-- Found PkgConfig: /usr/bin/pkg-config (found version "0.29.1")
-- Checking for module 'cfitsio'
-- Found cfitsio, version 4.0.0
CMake Error at /usr/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find GSL (missing: GSL_INCLUDE_DIR GSL_LIBRARY GSL_CBLAS_LIBRARY)
(found version "2.7+")
Call Stack (most recent call first):
/usr/share/cmake-3.22/Modules/FindPackageHandleStandardArgs.cmake:594 (_FPHSA_FAILURE_MESSAGE)
cmake/modules/FindGSL.cmake:158 (find_package_handle_standard_args)
CMakeLists.txt:93 (find_package)

-- Configuring incomplete, errors occurred!
See also "/home/laheller/android-repos/stellarsolver/_build/CMakeFiles/CMakeOutput.log".

As you can see I am exporting PKG_CONFIG_PATH variable and setting its value find all the dependencies.

Any idea, why it does not work for GSL ?

BR,

Ladislav

[rlancaste]

I don't know if this is relevant or not, but sometimes when people have trouble finding GSL on their systems, it's because they don't have the dev version of GSL installed. Is that an option on Android?

[laheller]

@rlancaste

I have this version:
https://www.gnu.org/software/gsl/#development

I built this for Android and as output I have headers and library files as usual.

BTW there is a note on the above page, that the gsl build should be configured with:

./configure --enable-maintainer-mode

Is that maybe required? I did not start configure with the above switch.

[rlancaste]

Were you able to get this to work on Android?

[laheller]

Hi @rlancaste

I was not able to build this project for Android. It always failed to detect GSL library.
As I wrote earlier, I only built the original astrometry.net suite.

BR,

Ladislav